LLM Circuit Finder: Duplicate 3 layers to boost reasoning without training

✍️ OpenClawRadar📅 Published: March 19, 2026🔗 Source
LLM Circuit Finder: Duplicate 3 layers to boost reasoning without training
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The llm-circuit-finder toolkit implements and extends David Ng's RYS method to discover and exploit 'reasoning circuits' hidden inside transformer models. The core finding: certain contiguous blocks of layers act as indivisible cognitive units. Duplicating them in the forward pass - same weights, no training, no merging - makes models measurably smarter on specific capabilities.

Key Results

Devstral-Small-2-24B with layers 12, 13, 14 duplicated once:

  • BBH Logical Deduction: 0.22 → 0.76 (+245%)
  • GSM8K (strict): 0.48 → 0.64 (+33%)
  • MBPP (code gen): 0.72 → 0.78 (+8%)
  • Average improvement: +8% across all metrics with nothing degraded

Qwen2.5-Coder-32B with layers 7, 8, 9 duplicated once:

  • Reasoning probe (causal + logic + nav): 76.5% → 94.1% (+23%)

How It Works

Transformers organize themselves during training into functional circuits - multi-layer processing units that perform complete cognitive operations. These circuits are indivisible: duplicating a single layer does almost nothing, but duplicating the right block of 3-4 layers gives the model a second pass through its reasoning pipeline.

Different models have different circuits in different places:

  • Devstral-24B (40 layers): reasoning circuit at layers 12-14
  • Qwen2.5-32B (64 layers): reasoning circuit at layers 7-9

The boundaries are sharp. Shift the block by one layer in either direction and the improvement disappears or inverts.

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Different Duplication Patterns Create Different Modes

Same weights on disk, same VRAM for the base model, just different routing:

  • Double-pass 13-16: Math ↑↑, EQ ↑
  • Triple-pass 13-16: Math ↑, EQ ↑↑
  • Interleaved 13,13,14,14,15,15,16: Math ↑↑↑, EQ ↓ (pure math mode)
  • Quadruple-pass 13-16: Math —, EQ ↑↑ (EQ mode, math neutral)

Quick Start

Find circuits in your model:

pip install gguf requests tqdm
python sweep.py \
  --model /path/to/model.gguf \
  --llama-server /path/to/llama-server \
  --tmpdir /dev/shm/rys \
  --results pass.jsonl \
  --block-sizes 3 4 5 \
  --stride 1 \
  --start-min 10 --start-max 20 \
  --skip-baseline \
  --port 8099 \
  --server-args --device Vulkan1,Vulkan2

Apply a known circuit:

# Duplicate layers 12-14 in Devstral
python layer_path.py model.gguf improved.gguf \
  -p " 0..14,12,13,14,15..39 " -v

Duplicate layers 7-9 in Qwen2.5-32B

python layer_path.py model.gguf improved.gguf
-p " 0..9,7,8,9,10..63 " -v

Triple-pass example

python layer_path.py model.gguf experiment.gguf
-p " 0..16,13,14,15,16,13,14,15,16,17..39 " -v

Validate with established benchmarks:

# Start the server with modified model
llama-server -m improved.gguf --port 8089 -ngl 99 --device Vulkan1,Vulkan2
# Run lm-evaluation-harness

The entire discovery process - sweep, discovery, validation - was done on two AMD consumer GPUs (RX 7900 XT + RX 6950 XT) in one evening.

📖 Read the full source: HN LLM Tools

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👀 See Also